Double sites occupancy of Mn4+ in Cs2NaAlF6 with enhanced photoluminescence for white light-emitting diodes.

In this work, we present a novel single-phase red phosphor of Cs 2 NaAlF 6 :Mn4+ with two Al3+ lattice sites, which shows two groups of vibrational phonon sidebands and ultra-intense zero phonon line (ZPL) under blue light illumination. The evidences have shown that the interesting spectral features originate from the non-equivalent occupation of Mn4+ for both Al3+ sites, which induces the neighboring cation vacancies surrounding Mn4+ and highly distorted [MnF 6 octahedral in the Cs 2 NaAlF 6 host. The luminescent behavior of double sites occupied by Mn4+ can absorb researchers' interest on novel red-emitting phosphors. Profiting from the photoluminescence (PL) features, superior color rendering index of R a = 90.3, R 9 = 81, and low correlated color temperature of T c = 3967 K are achieved from white light-emitting diode (LED) by using yellow Y 3 Al 5 O 12 :Ce3+ (YAG) and red Cs 2 NaAlF 6 :Mn4+ phosphors as blue light converters. These results suggest that Cs 2 NaAlF 6 :Mn4+ for phosphor has a stupendous potential for LED lighting. A novel red phosphor of Cs 2 NaAlF 6 :Mn4+ with unprecedented spectral features of double vibrational phonon sidebands and ultra-intense ZPL comparable to the sharpest v 6 peak under blue light excitation was obtained. The amazing spectral feature is originated from the non-equivalent occupation of Mn4+ for both Al3+ sites in CNAF host. Profiting from the extraordinary PL properties, excellent optical performance of CNAF:Mn as color converter is achieved, implying its potential application in white LED lighting or display devices. Image 1 • A novel red-emitting phosphor of Cs 2 NaAlF 6 :Mn4+ has been successfully synthesized. • The crystal structure of Cs 2 NaAlF 6 :Mn4+ has been confirmed. • The spectral feature with ultra-intense zero phonon line has been elucidated. • Double sites occupancy of Mn4+ in Cs 2 NaAlF 6 has been verified. [ABSTRACT FROM AUTHOR]